1. Field of the Invention
The present invention relates to a method of manufacturing a field emission device, and more particularly, the present invention relates to a method of manufacturing a field emission device having an increased lifetime by preventing the degradation of Carbon NanoTubes (CNTs).
2. Description of the Related Art
A field emission device emits electrons from emitters formed on a cathode electrode by forming a strong electric field around the emitters. An example of an application of a field emission device is a Field Emission Display (FED), which displays an image using visible light generated by the collision of electrons emitted from the field emission device to a phosphor layer formed on an anode electrode. Due to the excellent characteristics of FEDs, such as thinness, that is, an overall thickness of an FED is only a few cm, a large viewing angle, low power consumption, and low manufacturing costs, FEDs are expected to be one of the next generation display devices together with Liquid Crystal Displays (LCDs) and Plasma Display Panels (PDPs).
The FEDs can also be used in a BackLight Unit (BLU) of an LCD that displays an image on a front surface of the LCD when light emitted by a light source located in the rear of the LCD is transmitted through liquid crystals that control the rate of optical transmittance of the light. The light source located in the rear of the LCD can be a Cold Cathode Fluorescence Lamp (CCFL), an External Electrode Fluorescence Lamp (EEFL), or a Light Emitting Diode (LED). Besides these, a field emission type backlight unit can also be used as the light source. The field emission type backlight unit in principle has an identical driving mechanism and a light emission mechanism as the field emission device. However, the difference is that the field emission type backlight unit does not display an image but only functions as a light source. Due to its thinness, low manufacturing costs, and location-selective brightness control function, the field emission type backlight unit is expected to be a next generation backlight unit for LCDs. The field emission devices can also be applied to various systems that use electron emission, such as X-ray tubes, microwave amplifiers, flat panel lamps, and the like.
A micro tip formed of a metal, such as molybdenum Mo, is conventionally used as an emitter to emits electrons in a field emission device. However, Carbon NanoTubes (CNTs) having high electron emission characteristics are now mainly used as electron emitters. Field emission devices that use CNT emitters have advantages of low manufacturing costs, a low driving voltage, and high chemical and mechanical stability. The CNT emitters can be formed in a paste form or by directly growing the CNTs using a Chemical Vapor Deposition (CVD) method. The forming of the CNTs in a paste form has a drawback in that the lifetime of the field emission device is reduced since the CNTs are degraded in the process of removing an organic material and a binder that constitute the paste. The method of direct growing of the CNTs has an advantage in that the degradation of the CNTs can be prevented since an organic material or a binder that constitute the paste is not employed in this method. However, due to a high growing temperature and complicated synthesizing conditions, mass production is difficult.